A conventional device is described with reference to FIG. 12. FIG. 12 is a sectional view of a conventional loud speaker. An internal magnetic circuit 4 is formed by sandwiching magnetized magnet 1 between upper plate 2 and yoke 3 in FIG. 12. Frame 6 is bonded to yoke 3 of magnetic circuit 4.
Diaphragm 7 is bonded to a rim part of frame 6, voice coil 8 is bonded to diaphragm 7, and voice coil 8 is engaged in and bonded to magnetic gap 5 in magnetic circuit 4. Protector 9 is bonded to frame 6 so as to cover diaphragm 7.
As an example of a conventional device related to the present invention, reference is made to Japanese Patent Unexamined Publication No. S61-258600.
The loud speaker is often used in an electronic apparatus such as a portable phone. When the loud speaker is affected by electromagnetic waves, the electromagnetic waves coming from voice coil 8 of the loud speaker, are amplified by an amplifier of the electronic apparatus such as the portable phone, generates a noise component, and causes electromagnetic interference, disadvantageously. These phenomena often occur especially in a GSM (global system for mobile communications) portable phone.